Shortest barrel length upper?

[openbolt]

Does anyone know of an upper with a rifle length gas system with a barrel shorter than 18 inches? Is that even possible?

LDB,

I can answer one of your questions with first hand knowledge..

Back in the day when I lived in the San Diego area Tim LaFrance took my 20" 1/12" twisted Colt pencil barrel and cut/re-crowned/re-threaded it to 16". It ran 100% up until i shot it out. That Colt semi auto rifle came with me several decades ago when I relocated to Idaho. The very 1st transferable Colt M-16 I bought ($2200.00) ended up with the upper in question. Naturally being new to machine guns I ran it really hard that first year. Being in a free state on a few acres of my own land, my home was my range.. you can imagine my enthusiasm.

Long story short it ran perfect up until it gave up the ghost and died. So yes, It can be done if you know what you're doing (Tim LaFrance). Give it to someone new to automatic fire on his own piece of land in a free state...you got a recipe for a burnt out barrel. I wish I still had it, great configuration...I'm talking about balance, handling characteristics & sight radius. This was before RDS and flat top uppers. It was a great set-up. That said...you'd be better off with a 16" mid-gas today.

Hope this helped answer your query.

openbolt

[Mr. Goodtimes]

So many replies, so little responsive content. Thank you all for so much useful and helpful information.

That’s because this topic has been covered about 8,000,000,374,081 times with the exact same conclusion every time. The answer hasn’t changed.


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[openbolt]

That’s because this topic has been covered about 8,000,000,374,081 times with the exact same conclusion every time. The answer hasn’t changed.

So I should refrain from helping this individual because his question has been asked & answered in the past and because you say so? Why does this bother you to the point of being rude about it? He asked I answered. No skin off your nose. If your unhappy just keep on walking...

[LDB]

Thank you for some very helpful replies. Yes, I am very new to this. I shot 4 magazines through an M16 in college 41 years ago when I took an ROTC class in lieu of a PE class. I haven't fired one since. I'm just beginning the learning phase. The dwell explanations help significantly as I now have something tangible to understand.

I'm sure I'll likely ask any number of questions that are reruns but one can only read and learn so much and the amount available here is pretty enormous. If I wait until I've surfed and read and learned the entire site's offering of information to ask questions I'll probably be old(er) and dead. So I think I'll ask as I go along and be thankful to those who remember being new and not knowing everything and are willing to answer and help a new guy.

[MistWolf]

...The entire process has to happen before the bullet leaves the barrel, and your pressure falls to zero. Once the bullet leaves, you have no pressure left in the system...

This is incorrect. First, if the entire process had to happen before the bullet uncorked the muzzle, any extra distance from gas port to muzzle, or the addition of a suppressor, would make no difference to gassing.

Second, it takes time for the rifle to vent all the gasses after the bullet uncorks the muzzle. Gas operated firearms (except blow back systems) run off of residual pressure and the action doesn't begin moving until after the bullet uncorks the muzzle.

[Firefly]

A lot has changed since the 40s.

Honestly, I'd get either a 6920 or a BCM middy and just not worry about it.

The original 605 CAR-15 looks interesting and imspired the Dissipator but it came at a cost.

As a neophyte, you can get turned off super quick sweating the details. Never has a rifle system existed so that could be so customized. The inherent issue with that is the overlap between what we think we want, what seems like a good idea, and what is actually useful.

Either a baseline 6920 or a BCM middy with Troy iron sights will cover any need you have for recreational shooting.

At the end of the day my Colt is pretty plain but hits true. In the words of Poet Warrior Liz Phair "Don't look sexy but it just feels right".

Like for a 5.56, it really is my go to just because I have so much time behind it.

Although if I wanted a rifle just to shoot and didnt want to get all tactical practical; Aero has a good deal on 20" A4s and factory Colts aren't that much more. It's a good honest rifle with good honest sights. Then just shoot it a lot and get kinda jaded on it.

The 'prettier' an AR is, the more likely it is a safe queen.

[Eurodriver]

The 'prettier' an AR is, the more likely it is a safe queen.

I disagree, because there is nothing prettier than my 6920 when I'm done with it innaswamp.

[mack7.62]

Another thing that seems to be overlooked in these discussions is environmental conditions, the carbine 14.5 and rifle 20 are optimized to operate in a wide temperature range and under adverse conditions proven by testing. I like the 14.5 middy but will it be reliable at -60 or +140, ARAIK no tests have been done. And yes I know there is minuscule chance of a civilian needing to perform under these conditions, unless of course your rifle is inside the trunk of a black car in the middle of a Texas or Arizona summer or a Wyoming winter. I do wish data was available on some of these non standard configurations.